STOCK MYCOPLASMA BOVIS
Left: The number of farms known to be infected with M. bovis has been very low for quite some time.
‘It had a head start’ Scientists are optimistic, but not complacent, that the prevalence of Mycoplasma bovis is now very low on New Zealand farms. Elaine Fisher reports.
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re-border protocols, including PCR testing and treating semen with antibiotics, aim to help minimise the risk of Mycoplasma bovis re-entering New Zealand, Ministry for Primary Industries’ Chief Science Adviser Dr John Roche says “Now we can have batches of semen tested before it is sent here or have it treated with antibiotics that inactivate the bacteria, if it is present and viable. That, together with on-going research, is giving greater confidence,” he told the Tauranga Moana Biosecurity Capital forum “Readiness & Response in a Pandemic: the Application of Science”, held on-line in mid-October. Protocols for the use of new testing procedures have been established; in particular, a PCR test validated by the National Centre for Biosecurity and Infectious Disease in Wallaceville. M. bovis is spread animal-to-animal and because there is no longer any live animal trade into NZ, that risk has been removed from the border. “However, one avenue of concern is the
Mary van Andel, MPI chief veterinary officer.
illegal pathway. We don’t know if M. bovis came here via a legal or illegal channel, but it is a challenge to shore up all points of entry. M. bovis took a long time to come in the first place and we have strengthened the border even further.” From July 1, 2018, when the decision was made to eradicate and the programme was stood up, $523m has been spent on operational and compensation payments. By October this year, $211.7 million had been paid in compensation with 2,676 claims paid and completed and a further 23 being processed. In total 172,816 cattle have been culled. As of October 24, 2021, there were just four “M. bovis Active Confirmed”
Dairy Exporter | www.nzfarmlife.co.nz | December 2021
properties in NZ, John said. “That’s good news. The number of farms known to be infected with M. bovis has been very low for quite some time. Now we are at the tail of the disease, we are looking harder and harder and finding less and less infections. We have got reason to be quietly confident that there is a low national prevalence of M. bovis. This is cause for cautious optimism, but not room for complacency.” In total M. bovis has been found on 272 farms of which 268 are now ‘cleared confirmed properties’. In October 2021 there were no active properties in the North Island, and four in the South Island. The disease probably arrived in the country in 2015 or 2016 and was discovered in July 2017. “It had a head start and our response needed to catch up to find, contain and control the infection that was out there.” The success to date was credit to the tremendous MPI team of disease management experts and staff, working collectively with industry organisations and farmers, he said, making special mention of MPI chief veterinary officer, Mary van Andel for her strategic leadership of the M. bovis response. “We were able to share the learnings we had from tackling M. bovis with the Covid-19 response team. Many of our experts were seconded back and forth across government departments to provide important insight into tracing, testing systems and communications.” M. bovis is difficult to diagnose in an individual animal, as clinical signs are not seen in all infected animals, so collecting samples for diagnostic testing is necessary to identify groups of infected animals. The two tests used to detect M. bovis are: • ELISA test (Enzyme Linked Immunosorbent Assay) • PCR test (Polymerase Chain Reaction) which is the same type of test used to identify Covid-19. Background surveillance for the disease continues and John said less than 0.5% of commercial dairy herds react on BTM (bulk tank milk) ELISA tests. Since monthly BTM 71
